in Australia, wooden poles make up the majority of poles used as structural Supports for power transmission and telecommunications lines. The service life of poles is greatly reduced by biodegradation processes at ground level caused by fungal decay such as soft rot, white and brown rot and termite attack by damp wood and dry wood termites. Due to the high capital investment involved in these structural poles, and the cost of repairing and replacing these poles, it is therefore desirable to treat the poles in some way to combat biodegradation in wooden poles and greatly increase their service life. It has even been found that poles treated with wood preservative chemicals prior to installation can have a longer service life if they are inspected regularly and given further remedial treatment during the life of the pole.
Known methods for the remedial treatment of wooden poles have involved pouring treatment liquids such as creosote onto the surface of the pole and into the back-fill of the soil. This method has been found to be unsatisfactory as it relies on migration of the treatment chemicals from the soil into the wood and generally requires regular treatments about every two years. This method is further unsatisfactory as most of the chemicals used, leach into the soil away from the pole and do not serve their intended purpose and create an environmental hazard.
The most effective means of controlling fungal decay and termites is to apply a wood preservative containing bandage or applicator. In principle these bandages offer the most direct method of delivering chemicals to the wood whereby the chemical diffuses freely into the wood.
The principle elements required for any biodegradation of wooden structures are moisture (generally above about 20% nutrients and air. Consequently bandages are positioned at ground level as this is where the wood structures are most susceptible to fungal decay and termite attack.
Bandages supplied in rolls with diffusible chemicals bonded as dry powder mix to a weather impermeable sheath have been used in Europe and U.S.A. in addition preservative liquid or paste have been used onto wood structures as remedial treatments. These preservatives are either incorporated into a bandage or applied onto the timber surface by brushing or spraying. As the chemicals are exposed prior to being applied to the pole, users are required to wear protective clothing to avoid contact with the chemicals. This is seen as a disadvantage especially in climatic conditions where protective clothing is uncomfortable to wear. Other bandages have been developed which have been generally cumbersome and difficult to apply thus limiting their appeal to the industry. The ideal bandage should be weatherproof, exclude ground water and not be hazardous to the user, the environment or the general public.
Wood preservative bandages which impregnate an inert matrix with chemical must not only support the chemical but also must be sufficiently thick to be able to contain a satisfactory dosage of chemical. This makes a chemical impregnated bandage difficult to shape to the contours of a wooden structure and apply.